This application relates to structures, which may be hand tools or tool parts, and methods of making same, and particularly to tools formed of non-metallic materials. This application discloses an improvement of tools disclosed in copending U.S. application Ser. No. 09/005,680, filed Jan. 12, 1998, and entitled “Composite Socket with Duel Inserts and Annular Reinforcing Member”, now U.S. Pat. No. 6,029,547, the disclosure of which is incorporated herein by reference.
That prior application discloses a socket tool body formed of a glass-fiber reinforced nylon material with insert molded metal inserts in both of the driving and driven ends thereof, and with metal or rigid plastic reinforcing members disposed so as to encompass one or both inserts. These reinforcing members are provided, since it had been found that, under very high torque loads, such insert-molded socket tools might tend to fail by fragmenting apart. It is believed that this occurred by reason of fracture lines propagating along knurls on the outer surfaces of the inserts, causing portions of the surrounding plastic material to break away. The reinforcing members inhibited such fragmentation and, in certain embodiments, further inhibited propagation of fracture lines under high torque loads.
However, the embedment of the reinforcing members in the socket body requires a separate insert molding operation, with a separate set of mold tooling. In the case of plastic reinforcing members, an alternative process could be to use two nozzles which inject two dissimilar materials at timed intervals into the mold, but this also requires a higher tooling expense.
Apart from reinforcement, the formation of tools or tool parts of dissimilar inner and outer materials has also been used for other purposes, such as electrical insulation, improved hand grips and the like. Formation of these tools and tool parts has also typically required plural-step molding operations.